net: fec_mxc: Skip recv packet process when fec is halted

net: fec_mxc: Skip recv packet process when fec is halted

After FEC is halted by calling fec_halt callback, we should not continue
receiving packet. Otherwise it will process previous pending interrupts
on EIR register and uses wrong rbd index as this has been reset to 0.

The GRA interrupt which is triggered by issuing graceful stop command to
FEC transmitter in fec_halt is processed in this case. It causes wrong
receive buffer descriptors be used by FEC in next time.

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>